蒸散是连接水圈、大气圈和生物圈能量和水分交换的重要物理过程。基于遥感地表温度的区域蒸散反演是研究的热点和难点。基于植被覆盖度(VFC)和地表温度(LST)特征空间的蒸散模型方法是一类重要模型方法。此类模型的应用面临几个关键问题：一是模型仅适用平坦均一的下垫面；二是特征空间理论边界的确定存在较大的模糊性，模型应用具有极大的不确定性。对此，本项目提出开展野外试验和陆面过程模拟分析，研究不同覆盖度、水分供给条件下，地表温度变化规律及其与下垫面生物物理参数的关系，开展VFC/LST特征空间的深入研究。建立特征空间理论极限点的模拟方法，构建单个像元的理论VFC/LST特征空间；基于理论特征空间改进混合温度分解方法，实现双源遥感蒸散模型的构建。最后，结合卫星遥感数据实现区域土壤蒸发和植被蒸腾的反演研究。研究结果可扩展VFC/LST特征空间模型的应用范围，为区域水资源规划管理、生态环环境建设提供支撑。

Evapotranspiration (ET) is the most important process which relates to energy exchange and mass transfer between hydrosphere, atmosphere, and biosphere. Estimating land surface evaporation using remotely sensed surface temperature is a hot and difficult research point. Spatial contextual model based vegetation fractional cover - land surface temperature space (VFC/LST) is one of the important ET modeling approaches. However, two critical issues are related with the application of the VFC/LST based ET modeling approaches: (1) the application of this type of models are restricted to a spatially homogeneous surface; (2) the determination of the VFC/LST boundary involves great ambiguity and cause large uncertainties to ET estimation. The objective of the project is to investigate the variations of the land surface temperature, and to study the relationship between land surface temperature and land surface biophysical parameters based on filed experiment and land surface model simulation. A method to simulate four extreme points of VFC/LST will established and a theoretical VFC/LST space will be determined for each pixel. Based on the theoretical VFC/LST space, the temperature decomposition method will be improved and a two source evapotranspiration model will be proposed. At last, using remotely sensed data and regional meteorological data, the regional soil evaporation and vegetation transpiration will be estimated using the newly developed two source ET model. The results will greatly promote the application of the VFC/LST based ET modeling approaches to heterogeneous surfaces and would definitely benefit to water resource management and ecological environment development.